Coupling for shaver drive shaft and cutter

ABSTRACT

A dry-shaver having a movable connection between the driving shaft and the cutting member, wherein the free end of the shaft is shaped as a coupling pin and provided with convexly curved lateral surfaces that fit bearingly in a prismatic aperture provided in a portion of the cutting member.

United States Patent 1 Kuiken et al. July 31, 1973 COUPLING FORSHAVER-DRIVE SHAFT AND CUTTER [56] References Cited [75] Inventors:Hendrik Kuiken; ,Wytse Bergsma, "UNITED STATES PATENTS both of Drachten,Netherlands 3,399,453 9/1968 Biesma 30/436 73 As U.S. Phl' C t' N Y k, l1 Sigma orpora ew or Primary Examiner0thell M. Simpson Attorney-Frank R.Trifari [22] Filed: Aug. 30, 1971 211 App]. No.: 176,285 ABSTRACT Adry-shaver having a movable connection between the Rained U's'.ApphcahonData driving shaft and the cutting member, wherein the free [63] s z zof July 1969' end of the shaft is shaped as a coupling pin and pro- 3 anone vided with convexly curved lateral surfaces that fit bearingly in aprismatic aperture provided in a portion 52 US. Cl. 30 43.6 is]; int. ClB67b 7/38 the cum"; membe" [S8] Field of Search .Q. 30/32, 43.4-43.6 10Claims, 5 Drawing Figures f 46 m 1\\\\\\\\\\\ Y\\\\\\\\\\ i PATENTEU m31 summfz INVENTOR) HENDRIK KUIKEN WYTSE BERGSMA 1 COUPLING FOR SHAVERDRIVE SHAFT AND CUTTER This application is a continuation of Ser. No.842,104 filed July 16, 1969, now abandoned.

This invention relates to a dry-shaver having at least one shaving headwhich is actuated by a driving shaft; in the shaving head is ashearplate assembly capable of assuming an inclined position relative to thedriving shaft with a cooperating rotatable cutting member held inengagement with the shear plate; holder portion of the cutting membercarries cutters and an aperture in r the cutting member is movablyconnected with a free end of the driving shaft shaped in the form of acoupling pin.

In one known movable connection between a driving shaft and a cuttingmember, there is the disadvantage during the operation of thedry-shaver, that the cutting member is not always in complete engagementwith the associated shear, plate, with the result that during theoperation a rocking movement of the cutting member relativeto the shear.plate is produced preventing all the hairs protruding through the shearplate from being cut. The above rocking movement, which is experiencedby the user as a vibration of the shear plate, is also responsible foruneven wear of the shear plate relative to the cutting member, so thatthe existing situation of inaccurate engagement of the cutting memberand the shear plate is aggravated.

It is an object of the invention to eliminate these disadvantages as faras possible, and the invention is chara'cterized in thatthe'above-mentioned movable connection is established with the couplingpin, formed at its sides or lateral faces with convex curved surfacesthat fit bearingly into the prismatic aperture in the cutter-carryingholder of the cutting member.

Thus, a very simple movable connection is obtained between the drivingshaft and the cutting member, which connection permits an inclinedposition of the cutting member relative to thedriving shaft in more thanone direction, while permitting satisfactory engagement of the cuttingmember with the shear plate during the operation of the dry-shaver.

The establishment of such a movable connection between a driving shaftand a cutting member of a dryshaver is known from the prior artdisclosure, Austrian Pat. No. 197,239; here a thin shaft which is bentseveral times in a plane has a straight centre portion which issupported for rotation in a slot in the end of the driving shaft.

This prior reference is comparatively complicated and requires the useof several components, with a resulting high cost of manufacture, incomparison with the construction according to the present invention. Afurther disadvantage of this prior design is difficulty in centering thecutting member relative to the driving shaft, which becomes manifestwhen component parts have to be replaced.

A permanent and satisfactory centering of the driving shaft relative tothe cutting member, even on reassembly after dismantling, has beenachieved with the present invention; the coupling pin has two pairs ofopposite lateral, convexly curved surfaces. One pair of these oppositefaces form part of the curved surface of a circular cylinder having adiameter which is substantially equal to one side of the rectangularaperture provided in the cutter-carrying holder portion of the cuttingmember, the convex surfaces of the other pair of opposite lateral facesform part of the curved cylindrical surface of another circular cylinderhaving a diameter which is substantially equal to the other side of thesaid rectangular aperture in the cutting member, while in the assembledcondition the centers of the driving shaft, of said cylinders, and ofthe spherical surface on which lie the eight vertices of the rectangularaperture coincide.

An embodiment which provides very satisfactory results in practice, ischaracterized in that the convexly curved surfaces of only one pair ofopposite lateral faces form part of a spherical surface having adiameter which is substantially equal to the longer side of a prismaticor rectangular aperture of the cutting member, and the convex curvedsurfaces of the other pair of opposite faces form part of the surface ofa circular cylinder having a diameter which is substantially equal tothe shorter side of the said aperture provided in the cutting member,while the centers of the said spherical surface, of the said cylinder,and of the spherical surface, of the said cylinder, and of the sphericalsurface on which lie the eight vertices of the rectangular aperturecoincide in the assembled condition.

The coincidence of the said centers during each I movement and positionof the cutting member relative to the driving shaft ensures satisfactoryand permanent centering The invention will be further described withreference to the accompanying schematic drawings, which show severaladvantageous details of one embodiment.

FIG. 1 is a fragmentary elevation view in section of the shaving headand of the driving shaft which has a free end inthe form of a couplingpin; the center portion of this view was taken along a cutting plane I-Iof FIG. 5 the shorter sides of the rectangular aperture of the cuttingmember, 7

FIG. 2 is a view similar to FIG. 1, but taken along a cutting planeparallel to the longersides of the aperture,

FIG. 3 is a view similar to that of FIG. 1, however, the driving shafthas a certain angular displacement relative to the cutting member,

FIG. 4 is a view similar to that of FIG. 2, however the driving shafthas a certain angular displacement relative to the cutting member, and

FIG. 5 is a top'plan view of the coupling pin when positioned withinsaid aperture.

Referring now to FIG. 1, a cutting member 1 of a shaving head isconnected with a free end of a driving shaft 3, which end is shaped toform a coupling pin 2.

FIGS. 3 and 4 show that this connection is movable.

The coupling pin, which has lateral faces shaped as convex surfaces,extends into a rectangular, prismatic aperture 6 provided in portion 4of the cutting member 1 which includes cutters 4a that engage shearplate 4b. A cross-section of the aperture 6 defines a rectangle having apair of longer sides and a pair of shorter sides in FIG. 5. Thisaperture 6 is disposed centrally about the cutter-carrying holderportion 4 of the cutting member 1, and the coupling pin 2 is shaped incrosssection, so that its lateral faces barely engage the walls of theaperture, with each two opposite lateral faces forming an associatedpair. The curved surfaces of one pair form part of the curved surface ofa circular cylinder 11 which has a diameter substantially equal to theshorter side of the aperture 6 (see FIGS. 1 and 3).

13 of one pair of opposite faces being tangent to the opposite lateralfaces of the respective cylindrical surface 1 1, while the plane or flatpartial surfaces 12 of the other pair of opposite lateral facesintersect the oppo-.

site lateral faces of the respective spherical surface 10.

The coupling pin 2 is retained in its assembled position by a plate 7disposed across the aperture 6 of the cutting member 1, the innersurface 9 of the plate 7 engaging the facing surface 8 of the couplingpin 2, both during each movement of the cutting member 1 relative to thedriving shaft 3 and during the relative stationary condition of thesecomponents. In FIGS. 1 to 4, the plate 7 has remote parts adjacentsurface of the holder portion 4 of the cutting member 1, while the freeend 8 of the coupling pin 2 engages the center part of the plate. FIGS.3 and 4 show that the center of the spherical surface 10, the center ofthe cylindrical curved surface 11, and the center of the projectedspherical surface on which lie the eight vertices of the aperture 6 inthe holder portion 4 of the cutting memher 1, always coincide even in aninclined or angular displacement of the driving shaft 3 relative to thecutting member 1.

From this it will be clear that in this situation-also satisfactorycentering of the cutting member 1 relative to the driving shaft 3 ismaintained.

What is claimed is:

1. For use with a dry shaver including a housing and a drive shaft whichis rotatable about an axis and has an extending free end, a shaving headsecurable to the housing and movable between different inclinationsrelative to said axis, the shaving head comprising a shear plate withouter and inner surfaces, and a cutting member having a generallyrectangular aperture in the center thereof, said free end of the driveshaft engaging said aperture to function as a moving coupling, said freeend defining a coupling pin formed as a curved body having (in sideview) two curved ends forming arcs of a first circle extending laterallyas a circular cylinder and (in end view) two curved sides forming arcsof a second circle extending laterally as a circular cylinder of smallerdiameter than the first, the aperture having four walls that intersectforming eight vertices which define between them a central point, theintersection of the axes of said first and second cylinders and thiscentral point being coincident.

2. Apparatus according to claim 1 wherein the diameter of the firstcylinder is substantially equal to the length of one side and theaperture and the diameter of the second cylinder is substantially equalto the length of one end of the aperture.

3. Apparatus according to claim 1 wherein the cutter member is adjacentand facing the inner surface of the shear plate, and the cutter memberfurther comprises a retaining plate secured upon the upper surface andcovering said aperture, the coupling pin having a tip part that engagessaid retaining plate.

4. Apparatus according to claim 1 wherein said coupling pin has a topsurface that defines two intersecting planes, each of which alsointersects one of said end 4 parts of said pin, and two additional planeportions each of which is tangent to one side of the aperture andintersects both of said intersecting planes. 5. A dry-shaver having adriving shaft with a free end and at least one shaving head, which isactuated bysaid driving shaft, said shaving head comprising a shearplate capable of assuming an inclined position relative to the drivingshaft and a cooperating rotatable cutting member held in engagement withthe shear plate, said cutting member including a prismatic aperturetherein forming a movable connection with said freeend of the drivingshaft, which end is shaped so as to form 'a coupling pin, has its sidesprovided with convexly curved surfaces, which-fit bearingly in theprismatic aperture in the cutting member.

6. A dry-shaver as claimed in claim 5, characterized v in that theconvexly curved surfaces form part of two pairs of opposite .faces,which pairs intersect one another substantially at right angles, theconvexly curved surfaces of one pair of opposite faces forming part of acylindrical surface of a circular cylinder having a diameter which issubstantially equal to one side"oflthie aperture provided in the cuttingmember, which aperture has a rectangular cross-section, and the convexlycurved surfaces of the other pair of opposite faces forming part of thecylindrical surface of another circular cylinder having a diameter whichis substantially equal to the other side of the rectangular aperture inthe cutting member while the centers of the said cylinders and of thesphere on which lie the vertices of the rectangular aperture providedin-the cutting member coincide in the assembled situation of the drivingshaft.

7. A dry-shaver as claimed in claim 5, characterized in that theconvexly curved surfaces form part'of two cutting member, and theconvexly curved surfaces of the other pair of opposite faces formingpart of a cylindrical surface of another circular cylinder having adimaeter which is substantially equal to the other side of therectangular aperture in the cutter member, while the centers of thecylinders and of the sphere on which lie the vertices of the rectangularaperture provided in the cutting member coincide in the assembledsituation of the driving shaft.

8. A dry-shaver as claimed in claim 5, characterized. in that theconvexly curved surfaces form part of two pairs of opposite faces, whichpairs intersect one an other substantially at right angles, the convexlycurved surfaces of one pair of oppositefaces forming part of the surfaceof a sphere having a diameter which is substantially equal to the longerside of the prismatic aper ture provided in the cutting member, whichaperture has a cross-section in the form of a rectangular parallelogram,and the convexly curved surfaces of the other pair of opposite facesforming part of a cylindrical surface of a circular cylinder having adiameter which is substantially equal to the shorter side of the saidaper-' provided in the cutting member, this plate having an innersurface in line contact with the end of the cou- 1 pling pin facing thisinner surface both during any movement of the cutting'member relative tothe driving shaft and in the stationary relative condition of thesecomponent parts, whereby-the coupling pin is retained in its assembledposition.

v l l UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,748,731 Dated ul 1. 1973 Inventor('s) Hendrik Kuiken; Wvtse Berqsma Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

0n the title page, please insert after section (21) the following:

- (30) Foreign Application Priority Data July 26,. 1968 Netherlands.-.;6 8lO708- Signed and sealed this 30th day of July 1971p.

(SEAL) Attest:

McCOY M. GIBSON,JR. c. MARSHALL DANN Attesting :Oificer Commissioner ofPatents V .I

1. For use with a dry shaver including a housing and a drive shaft whichis rotatable about an axis and has an extending free end, a shaving headsecurable to the housing and movable between different inclinationsrelative to said axis, the shaving head comprising a shear plate withouter and inner surfaces, and a cutting member having a generallyrectangular aperture in the center thereof, said free end of the driveshaft engaging said aperture to function as a moving coupling, said freeend defining a coupling pin formed as a curved body having (in sideview) two curved ends forming arcs of a first circle extending laterallyas a circular cylinder and (in end view) two curved sides forming arcsof a second circle extending laterally as a circular cylinder of smallerdiameter than the first, the aperture having four walls that intersectforming eight vertices which define between them a central point, theintersection of the axes of said first and second cylinders and thiscentral point being coincident.
 2. Apparatus according to claim 1wherein the diameter of the first cylinder is substantially equal to thelength of one side and the aperture and the diameter of the secondcylinder is substantially equal to the length of one end of theaperture.
 3. Apparatus according to claim 1 wherein the cutter member isadjacent and facing the inner surface of the shear plate, and the cuttermember further comprises a retaining plate secured upon the uppersurface and covering said aperture, the coupling pin having a tip partthat engages said retaining plate.
 4. Apparatus according to claim 1wherein said coupling pin has a top surface that defines twointersecting planes, each of which also intersects one of said end partsof said pin, and two additional plane portions each of which is tangentto one side of the aperture and intersects both of said intersectingplanes.
 5. A dry-shaver having a driving shaft with a free end and atleast one shaving head, which is actuated by said driving shaft, saidshaving head comprising a shear plate capable of assuming an inclinedposition relative to the driving shaft and a cooperating rotatablecutting member held in engagement with the shear plate, said cuttingmember including a prismatic aperture therein forming a movableconnection with said free end of the driving shaft, which end is shapedso as to form a coupling pin, has its sides provided with convexlycurved surfaces, which fit bearingly in the prismatic aperture in thecutting member.
 6. A dry-shaver as claimed in claim 5, characterized inthat the convexly curved surfaces form part of two pairs of oppositefaces, which pairs intersect one another substantially at rIght angles,the convexly curved surfaces of one pair of opposite faces forming partof a cylindrical surface of a circular cylinder having a diameter whichis substantially equal to one side of the aperture provided in thecutting member, which aperture has a rectangular cross-section, and theconvexly curved surfaces of the other pair of opposite faces formingpart of the cylindrical surface of another circular cylinder having adiameter which is substantially equal to the other side of therectangular aperture in the cutting member while the centers of the saidcylinders and of the sphere on which lie the vertices of the rectangularaperture provided in the cutting member coincide in the assembledsituation of the driving shaft.
 7. A dry-shaver as claimed in claim 5,characterized in that the convexly curved surfaces form part of twopairs of opposite faces, which pairs intersect one another substantiallyat right angles, the convexly curved surfaces of one pair of oppositefaces forming part of a cylindrical surface of a circular cylinderhaving a diameter which is substantially equal to one side of theaperture of rectangular cross-section provided in the cutting member,and the convexly curved surfaces of the other pair of opposite facesforming part of a cylindrical surface of another circular cylinderhaving a dimaeter which is substantially equal to the other side of therectangular aperture in the cutter member, while the centers of thecylinders and of the sphere on which lie the vertices of the rectangularaperture provided in the cutting member coincide in the assembledsituation of the driving shaft.
 8. A dry-shaver as claimed in claim 5,characterized in that the convexly curved surfaces form part of twopairs of opposite faces, which pairs intersect one another substantiallyat right angles, the convexly curved surfaces of one pair of oppositefaces forming part of the surface of a sphere having a diameter which issubstantially equal to the longer side of the prismatic apertureprovided in the cutting member, which aperture has a cross-section inthe form of a rectangular parallelogram, and the convexly curvedsurfaces of the other pair of opposite faces forming part of acylindrical surface of a circular cylinder having a diameter which issubstantially equal to the shorter side of the said aperture provided inthe cutting member, while the center of the said sphere, the center ofthe said cylinder and the center of the sphere on which lie the verticesof the rectangular aperture provided in the cutting member coincide inthe assembled situation of the driving shaft.
 9. A dry-shaver as claimedin claim 5 characterized in that the curved surfaces of the lateralfaces of the coupling pin at their upper ends facing the holder portionof the cutting member terminate in plane surfaces.
 10. A dry-shaver asclaimed in claim 5 further comprising a plate arranged across theprismatic aperture provided in the cutting member, this plate having aninner surface in line contact with the end of the coupling pin facingthis inner surface both during any movement of the cutting memberrelative to the driving shaft and in the stationary relative conditionof these component parts, whereby the coupling pin is retained in itsassembled position.